This program project grant is an intradisciplinary approach to the evaluation of the effects of lead at low dose during pregnancy on neonatal outcome and subsequent development. Human population studies measure umbilical cord blood lead levels in a large cohort of newborns, and evaluate the relationship of lead exposure to the incidence of still births, prematurity, neonatal infection and other bad outcomes, controlling for other covariates which could confound. Animal models of prenatal exposure which systematically manipulate the dose of lead are employed. The pharmacodynamics and distribution of lead in various tissues with respect to time are studied. The neuroanatomic effects of doses of lead insufficient to produce weight changes in the host or histologic alterations are studied, using quantitative measures of synaptic development over time as the outcome of interest. The sequencing behavior of rats given analogous doses is measured by quantitative methods.